1. Field of the Invention
The present invention is based on a valve for controlling a connection in a high-pressure fluid system, in particular in a fuel injection apparatus for an internal combustion engine.
2. Description of the Prior Art
A valve of the type with which this invention is concerned, known from EP 0 840 003 A, serves to control a connection in a fuel injection apparatus for an internal combustion engine and has a valve member that is guided so that it can slide in the direction of its longitudinal axis, protrudes into a valve pressure chamber, and, in the valve pressure chamber, has a sealing surface at an end extending transversely in relation to its longitudinal axis. The sealing surface of the valve member cooperates with a valve seat extending transversely in relation to its longitudinal axis in order to close an opening encompassed by the valve seat in relation to the pressure chamber. In this case, high pressure prevails in the valve pressure chamber and the opening is adjoined by a duct leading to a low-pressure region; the valve member controls the connection of the valve pressure chamber to the low-pressure region, thus controlling the pressure in the valve pressure chamber. When the valve is open, i.e. when its sealing surface is lifted away from the valve seat, fuel flows out of the valve pressure chamber into the low-pressure region. The outgoing fuel generates forces acting on the valve member in the direction of its longitudinal axis that can cause the valve member to move uncontrollably in the direction of its longitudinal axis. This can make it impossible to precisely control the fuel injection, chiefly the injected fuel quantity, or can even result in a complete functional failure of the valve and therefore of the fuel injection apparatus. In addition, the high flow velocity of the fuel flowing out of the valve pressure chamber into the low-pressure region and the lack of optimal flow guidance in the known valve can lead to cavitation and therefore damage to the valve member and/or the valve seat.